The idgames archive is the Internet's largest collection of Doom WAD files and fan-made mods. Containing over 30,000 files collected over an almost 20 year period, the idgames archive is the product of thousands of individual fans of the Doom games. The archive also covers material for other games based on the Doom engine: Heretic, Hexen and Strife.
This snapshot of the archive was made in July 2013. For brevity, the archive here does not include the full contents of the idstuff/ subdirectory (which is a mirror of ftp.idsoftware.com and quite large). The archive can be browsed here